JPH07161055A - Optical pickup - Google Patents

Abstract

PURPOSE:To make a optical pickup to be of a super-thin form and to improve its dustproof characteristic by housing an optical assembly in the recessed part of a movable actuator. CONSTITUTION:An optical assembly 10 is formed so that a laser beam source 12a, an objective lens 14, a photodetector 12c receiving a reflected laser beam, etc., are attached to a hollow lens holder 11 whose base part is opened. The assembly 10 is housed in the recessed part 21a of the holder 21 of a movable actuator 20 to close tightly the opening part of the holder 11 and the surface of the holder 11 is made to form a flat plane with the surface of the holder 21. Thus, the optical pickup is made to the of the super-thin form and miniaturized and its dustproof characteristic is improved and optical members such as the beam source, the objective lens incorporated in the pickup are prevented from the stickings of dirt and dust.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup used in an optical disk device, and more particularly to an optical pickup in which an actuator is integrally attached with an optical system member for reading information from an optical disk.

[0002]

2. Description of the Related Art Conventionally, some optical pickups have been made ultra-thin by integrating an optical system member for reading information on an optical disk with a movable actuator. Hereinafter, a conventional optical pickup in which an optical system member is integrated with a movable actuator will be described with reference to FIG.
This will be described with reference to (b).

In FIG. 1, reference numeral 110 denotes a movable actuator, which is a hollow lens holder 111 having an opening formed on the bottom surface thereof, and an optical module 112, a reflection mirror 113a,
113b, objective lens 114, and focus coil 11
5a, 115b and tracking coils 116a-116
It has a configuration in which d is attached. In addition, the optical module 112 includes a light source that emits a laser beam and an optical disc 2.
A built-in photodetector for receiving the reflected laser beam from 00 (see FIG. 2). 120 is a fixed actuator,
A yoke 121 on which the movable actuator 110 is mounted,
Magnets 112a, which are attached to the protrusions at both ends of the yoke 121 and face the focus coils 115a and 115b and the tracking coils 116a to 116d,
And 112b. In addition, the movable actuator 110 includes four connecting members (wires) 131 to 131.
It is movably connected to the fixed actuator 120 by 134.

Next, a procedure for assembling the optical pickup having the above structure will be described. First, the lens holder 11
1, the objective lens 114 and the reflection mirrors 113a and 113
After b is bonded and fixed, the optical module 112 to which the flexible printed board 117 for signal extraction is soldered is positioned and fixed while adjusting the optical axis. Then, on one side of the outer circumference of the lens holder 111, the tracking coil 116a,
Focus coil 115a in which 116b is positioned and fixed
Is attached, and the movable actuator 110 is assembled by attaching the focus coil 115b to which the tracking coils 116c and 116d are positioned and fixed to the outer peripheral side surface of the lens holder 111. Next, the yoke 121
Magnets 122a and 122b are attached to the fixed actuator 120 to assemble the fixed actuator 120 and the movable actuator 110, and the connecting members 131 to
The parts are connected by 134 to complete the assembly work of the optical pickup.

[0005]

As described above, integrating the optical system member with the movable actuator is a very effective means for achieving an ultra thin optical pickup. However, in the above-described conventional optical pickup, the bottom surface of the lens holder 111 is open. Therefore, when the movable module 110 and the fixed module 120 are connected, the operator's finger enters the inside of the lens holder 111,
Since the optical system member may be soiled or deformed, it is necessary to pay close attention to the work so as not to cause such a problem, and there is a problem that productivity is poor.

Further, there is a problem that dust is likely to enter the inside of the lens holder 111 during use after assembly. Here, the dust adhering to the objective lens 114 from the front side of the lens holder 111 can be removed by a lens cleaner or the like, but from the inside of the lens holder 111, the optical module 112 and the reflection mirrors 113a, 11a are provided.
3b, the dust adhering to the objective lens 114 cannot be removed, so that there is a problem that the reliability of the optical pickup is lowered.

Incidentally, Japanese Patent Laid-Open No. 3-165334 and Japanese Patent Laid-Open No. 3-272031 propose an optical pickup in which an optical system member is housed in a box and sealed with a lid. With such a configuration, it is possible to prevent dust from adhering to the optical system member from the inside of the box body. However, such an optical pickup has a problem that the number of parts and the assembling process increase due to the provision of the lid, the productivity decreases, and the cost increases.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical pickup which can be made extremely thin and which can improve productivity, reliability, and dustproofness. .

[0009]

In order to achieve the above object, the optical pickup of the present invention has a hollow lens holder having a bottom opening, a light source for emitting laser light, and a laser emitted from the light source. An optical system assembly having an objective lens for focusing light on an optical disc and a photodetector for receiving reflected laser light from the optical disc, and a holder having a recess for accommodating the optical system assembly. , A movable actuator having a focus coil and a tracking coil for moving the holder in the focus direction or the tracking direction based on a signal from a control unit, and a yoke on which the movable actuator is mounted, facing the focus coil and the tracking coil. A fixed actuator to which the magnet is attached, and the movable actuator. And a connecting member that movably connects the fixed actuator to the fixed actuator, and preferably receives a reflected light beam from the optical disc, detects a tracking error or a focus error, and outputs a tracking error signal or a focus error signal. And a control unit that inputs a focus error signal or a tracking error signal from the error detection unit and outputs a signal to the focus coil or the tracking coil.

[0010]

According to the optical pickup of the present invention having the above-mentioned structure, the opening of the lens holder is sealed by accommodating the optical system assembly in the concave portion of the movable actuator. It is possible to prevent dirt and dust from adhering to optical system members such as lenses and reflection mirrors, thereby improving the productivity and reliability of the optical pickup. Further, with such a configuration, it is possible to protect the optical system member from dust without increasing the number of parts and the assembly process.

[0011]

Embodiments of the optical pickup of the present invention will be described below with reference to the drawings. 1A and 1B show an optical pickup according to this embodiment. FIG. 1A is an exploded perspective view, and FIG. 1B is a sectional view taken along the line A-A of FIG.

In FIG. 1, reference numeral 10 denotes an optical system assembly, which has a structure in which an optical module 12, reflection mirrors 13a and 13b, and an objective lens 14 are adjusted and arranged in a hollow lens holder 11 whose bottom is opened. Optical module 1
2 is attached to a through hole formed at one end of the upper surface of the lens holder 11, and as shown in FIGS. A detector 12c, a glass lid 12d for enclosing these members in a case 12f, and this crow lid 1
Hologram element adjusted on 2d (error detector)
It consists of 12e.

The light source 12a shown in FIG. 2A is, for example,
It is a semiconductor laser and emits laser light toward the prism mirror 12b. The prism mirror 12b is a light source 12
The laser light from a is reflected in the vertical direction, and the laser light is guided to a reflection mirror 13a described later via the hologram element 12e. The hologram element 12e is located above the photodetector 12c, as shown in FIG.
The reflected laser light from is diffracted and is transmitted to the photodetector 12c. The photodetector 12c has a plurality of light receiving portions, receives the reflected laser light diffracted by the hologram element 12e, performs a predetermined calculation, and outputs a focus error signal, a tracking error signal, and an information signal. . Further, the photodetector 12c includes the flexible printed board 15
It is connected to a control unit (not shown) of the apparatus via a.

The reflecting mirrors 13a and 13b are fixed to both ends of the hollow of the lens holder 11 in a state of being inclined at a predetermined angle, and reflect the laser light emitted from the optical module 12 or the reflected laser light from the optical disc 200 at right angles. Then, the optical disc 200 or the optical module 12 is guided.
The objective lens 14 is attached to a through hole formed at the other end of the upper surface of the lens holder 11, and focuses the laser light emitted from the optical module 12 onto the optical disc 200.

Reference numeral 20 denotes a movable actuator, which is a recess 2 for accommodating the optical system assembly 10 in the center of the holder 21.
1a is formed. Also, this recess 21a
Protrusions for holding the optical system assembly 10 at four points are formed on the inner peripheral surface of each. Further, a focus coil 22a having tracking coils 23a and 23b fixed thereto and a tracking coil 2 are provided on both side surfaces of the holder 21.
A focus coil 22b, to which 3c and 23d are fixed, is attached. The focus coils 22a and 22b and the tracking coils 23a to 23d are composed of a terminal flexible printed board (not shown) and connecting members (wires) 41 to 44 and a flexible printed board 15 which will be described later.
It is connected to the control unit via b.

Here, when the focus error signal is input from the photodetector 12c, the control unit supplies power to the focus coils 22a and 22b, and the focus coil 2
2a, 22b and magnets 32a, 32b of the fixed actuator 30 described later are electromagnetically operated to move the holder 21 in the focus direction (the arrow Y direction in FIG. 1B). Further, when the tracking error signal is input from the photodetector 12c, the control unit controls the tracking coil 23.
a to 23d to supply electric power to the tracking coil 23a
23d and the magnets 32a and 32b are electromagnetically operated to move the holder 21 in the tracking direction (the arrow X in FIG. 1B).
Direction).

The fixed actuator 30 has a focus coil 22 when the movable actuator 20 is placed.
a, 22b and a yoke 31 having a vertical surface facing the tracking coils 23a to 23d, and the yoke 31.
The magnets 32 attached inside the vertical surfaces of the
a and 32b, and a printed board 33 attached to one end surface of the outer circumference of the yoke 31. The connecting members 41 to 44 movably connect the movable actuator 20 to the fixed actuator 30 and guide the movable actuator 20 in the focus direction or the tracking direction.

Next, the procedure for assembling the optical pickup of the present embodiment having the above-mentioned structure will be described. The assembly of the optical pickup of the present embodiment is completed by individually assembling and adjusting the optical system assembly 10, the movable actuator 20, and the fixed actuator 30 and joining them.

In order to assemble the optical system assembly 10, first, the objective lens 14 and the reflection mirror 13a are attached to the lens holder 11.
Install 13b. Next, the terminal portion of the flexible printed board 15a is soldered to the output terminal of the optical module 12, and then the optical module 12 is fixed to the lens holder 11 while adjusting the optical axis, and the assembling work is completed. To assemble the movable actuator 20, first, the tracking coils 23a and 23b are provided on one side surface of the focus coil 22a.
And the tracking coils 23c and 23d are bonded to one side surface of the focus coil 22b. Next, the focus coils 22a and 22b are adhered to the mounting portions formed on both side surfaces of the holder 21, respectively, and the assembling work is completed. In assembling the fixed actuator 30, first, the magnets 32a and 32b are bonded to the inside of the vertical surface of the yoke 31 so as to face each other, and further, the yoke 31 is attached.
The printed board 33 is adhered to one end surface of the outer periphery of the above to complete the process.

Next, the movable actuator 20 and the fixed actuator 30 are connected by the connecting members 41 to 44. After that, the optical system assembly 10 is moved to the movable actuator 2
The optical system assembly 10 is lightly press-fitted into the recess 21a of 0.
And the movable actuator 20 are joined. Then, the gap between the optical system assembly 10 and the recess 21a is filled with an adhesive,
Dust is prevented from entering the optical system assembly 10 and the rigidity of the movable actuator 20 is increased. This completes the assembly of the optical pickup.

According to the optical pickup of the present embodiment having such a configuration, the opening of the lens holder 11 is sealed by housing the optical system assembly 10 in the recess 21 of the movable actuator 20. Inside the holder 11, the optical module 12, the reflection mirrors 13a, 13
b. Prevents dirt and dust from adhering to optical system members such as the objective lens 14. Therefore, it is possible to connect the movable actuator 20 and the solid-state actuator 30 without paying careful attention as in the conventional case, and it is possible to improve the productivity and reliability of the optical pickup.
Further, with such a configuration, it is possible to protect the optical system member from dust without increasing the number of parts and the assembly process.

The optical pickup of the present invention is not limited to the above embodiment. For example, photodetector 1
As the focus error detecting means and the tracking error detecting means by 2c, various detecting means such as a spot size method and a three-beam method can be considered in addition to a general knife edge method and push-pull method. Further, the connecting member is not limited to the wire, but a hinge, a parallel leaf spring, or the like may be used.

[0023]

As described above, according to the optical pickup of the present invention, the optical pickup can be made extremely thin, and productivity, reliability and dustproof can be improved.

[Brief description of drawings]

1A and 1B show an optical pickup according to an embodiment of the present invention, FIG. 1A is an exploded perspective view, and FIG. 1B is a sectional view taken along the line AA of FIG. Is.

2A and 2B show an optical module built in an optical pickup, wherein FIG. 2A is a perspective view and FIG. 2B is a partially enlarged perspective view.

3A and 3B show an optical pickup according to a conventional example, FIG. 3A is an exploded perspective view, and FIG. 3B is the same FIG.
FIG. 6 is a cross-sectional view taken along line BB during assembly of FIG.

[Explanation of symbols]

 10 Optical System Assembly 11 Lens Holder 12 Optical Module 12a Light Source 12b Prism Mirror 12c Photodetector 12d Glass Lid 12e Hologram Element (Error Detection Part) 13a, 13b Reflection Mirror 14 Objective Lens 15a, 15b Flexible Print Board 20 Movable Actuator 21 Holder 21a recess 22a, 22b focus coil 23a-23d tracking coil 30 fixed actuator 31 yoke 32a, 32b magnet 33 printed board 41-44 connecting member (wire)

Claims (3)

[Claims] 1. A hollow lens holder having a bottom opening, a light source for emitting laser light, and an objective lens for focusing the laser light emitted from the light source on an optical disc.
An optical system assembly to which a photodetector for receiving the reflected laser light from the optical disc is attached, and a holder having a recess for accommodating the optical system assembly, the holder is based on a signal from a control unit. A movable actuator having a focus coil and a tracking coil attached thereto for moving the focus coil or the tracking direction; and a fixed actuator having a yoke on which the movable actuator is mounted with the magnet facing the focus coil and the tracking coil, An optical pickup comprising: a connecting member that movably connects a movable actuator to a fixed actuator. 2. A reflected light beam from an optical disk is received,
An error detection unit that detects a tracking error or a focus error and outputs a tracking error signal or a focus error signal, and a focus error signal or a tracking error signal is input from this error detection unit and a signal is output to the focus coil or the tracking coil. The optical pickup according to claim 1, further comprising a controller. 3. The optical pickup according to claim 2, wherein the error detector is a hologram element.